Beyond "Do-They-Look-the-Same?" to "Do-They-Behave-The-Same?": Similarity Analysis and Assessment Across Interactive Critical Systems Behaviours

Similarity is a key property across two or more interactive systems. Indeed, interacting with similar systems can bring benefits (e.g., reduce learning efforts and training time), but also may raise issues (e.g., interference errors and higher cognitive load). Interactive systems may be similar, as they correspond to the same work and tasks but performed with different underlying systems such as the pilots’ tasks in the cockpit of an Airbus 320 and a Boeing 737. They may also be similar by design, as they belong to the same suite as, for instance, the Microsoft Office software suite, where several tools are designed to be used concurrently by the same users. Previous work on similarity has been focusing on the visual presentation of interactive applications, highlighting similarities and dissimilarities in terms of layout, shape, colours, ... of the user interface. This paper proposes a systematic and formal approach to analyse and assess the similarity between several interactive systems, focusing on their behaviours. To this end, we propose a tool-supported process that exploits both interactive formal system behaviour models and user task models. These models are analysed with the help of formal tools (model checking) to identify discrepancies and commonalities in their exhibited behaviours. Beyond, we compare the specific and generic behavioural properties of each model, which provide semantic and meaningful information about how similar they are and how they differ. The approach is applied to two similar critical command and control interactive systems for flight safety operations in the space domain.